ABASIC FRAMESHIFT IN DNA - SOLUTION CONFORMATION DETERMINED BY PROTON NMR AND MOLECULAR MECHANICS CALCULATIONS
ABASIC FRAMESHIFT IN DNA - SOLUTION CONFORMATION DETERMINED BY PROTON NMR AND MOLECULAR MECHANICS CALCULATIONS
复制标题
DOI：
10.1021/bi00431a009
复制
发表时间：
1989-03-07
期刊：
影响因子：
2.9
通讯作者：
FAZAKERLEY, GV
中科院分区：
文献类型：
--
作者：
CUNIASSE, P;SOWERS, LC;FAZAKERLEY, GV
我们已经确定了一个非自互补的寡脱氧核苷酸双链的三维结构，其中包含一个模型基本位点。该双链包含6个GC碱基对，加上一条链中心的基本位点，对应于一个基本移码。对非交换质子的二维核磁共振研究表明，基位两侧的鸟嘌呤碱基相互堆叠，并且基位旋转出螺旋。基位的H4”质子与鸟苷的糖质子在5”方向上发生了紧密的质子-质子相互作用，这使得游离糖的位置得以明确。在很短的混合时间内记录的NOESY光谱的NOE形成曲线被用来计算一组质子间距离。该数据集被纳入到通过分子力学计算的寡核苷酸结构的细化。在3”方向上，鸟苷的糖构象的两个不同构象是符合所有核磁共振数据所必需的。这两种构象中的一种只能通过在特定位置添加反离子来稳定。
We have determined the three-dimensional structure of a non-self-complementary oligodeoxynucleotide duplex that contains a model abasic site. The duplex contains six GC base pairs plus the abasic site at the center of one strand and corresponds to an abasic frameshift. Two-dimensional NMR studies on the nonexchangeable protons show that the guanine bases on either side of the abasic site are stacked over each other and that the abasic site is rotated out of the helix. Close proton-proton interactions are observed between the H4'' proton of the abasic site and sugar protons of the guanosine in the 5'' direction, which allows the position of the free sugar to be well-defined. NOE buildup curves from NOESY spectra recorded at very short mixing times were used to calculate a set of interproton distances. This data set was incorporated into the refinement of the oligonucleotide structure by molecular mechanics calculations. Two conformations that differ in the sugar conformation of the guanosine next to the abasic site in the 3'' direction were necessary to fit all the NMR data. One of these two conformations could only be stabilized by addition of counterions at specific sites.